This application relates to an environmental control system for an aircraft which utilizes both high and low pressure compressed air for uses on systems of an aircraft.
Environmental control systems utilize air tapped from the engine for use in various systems of the aircraft such as within the aircraft cabin. The systems typically selectively tap low pressure air from a lower pressure location, and higher pressure air from a higher pressure compressor location. The two locations are utilized at distinct times during the operation of a gas turbine engine, dependent on need, and available air.
Airflow tapped from the higher pressure locations is at temperatures higher than typically needed for an aircraft system and therefore requires cooling. An intercooler or heat exchanger is therefore required.
Airflow may also be diverted from core airflow for engine buffer systems. An engine buffer system provides air at a desired temperature and pressure to bearing locations within higher temperature sections of the engine. The airflow is provided to keep lubricant within the various bearing compartments and maintain compartment walls below a desired temperature.
Diversion of any airflow from the core flowpath requires conduits that add to structural and assembly complexity. Moreover, each tap from the engine structure can reduce overall engine efficiency.